Rated insulation voltage is 800 V, so it can sit on a 690 V bus without creeping — the 52.5 kA breaking capacity at 690 V confirms it holds the unit on the grid under worst-case bolted fault conditions at that voltage level. At 240 V the interrupting rating is 440 kA; at 415 V it is 330 kA, and at 500 V it is 220 kA. Those numbers are the short-circuit current rating (SCCR) the breaker can clear without self-destruction, and they govern the available fault current the upstream transformer can deliver to this panel position.
Trip unit and selectivity notes
The ETU320 is an electronic trip unit with a current adjustment range from 95 A minimum to 756 A maximum — those are the pickup settings for the long-time element, not the continuous rating of the breaker itself. The continuous current is fixed at 63 A by the frame and the thermal path; the trip unit settings govern the protection curve above that. For selectivity studies, the ETU320 gives you an I²t on/off for short-time delay, which lets you coordinate with downstream MCCBs or fuses.